MICKOCHEMISTR Y. 79 



insoluble in alcohol and glycerine, it is precipitated in the 

 form of well developed sphaerocrystals which often fill large 

 cell-masses, when parts of plants containing inulin are pre- 

 served for a time in one of these fluids. Such sphaerocrys- 

 tals may be observed on examining larger parts of plants, 

 as, for instance, halved Dahlia roots, which have lain several 

 weeks, or longer, in alcohol or concentrated glycerine. 

 After being kept for years in alcohol these are with diffi- 

 culty soluble in cold water, as Leitgeb (I, 136) has shown ; 

 while those in alcoholic material a few weeks old dissolve 

 pretty readily in it. But in hot water even old inulin sphae- 

 rites are easily soluble, so that they are readily distinguished 

 from the otherwise similar sphaerites of calcium phosphate 

 {cf. 96). If sections from alcoholic material of Dahlia 

 roots, which always contain calcium phosphate sphaerites 

 with those of inulin, especially near the cut surfaces of the 

 roots, be heated on the slide in water to the boiling point, 

 the inulin sphaerites dissolve almost instantly, provided the 

 sections are not too thick, while the sphaerocrystals of cal- 

 cium phosphate remain for a time quite unchanged. 



The inulin sphaerites are also soluble easily and without 

 residue in concentrated sulphuric acid, while those of calcium 

 phosphate are transformed by it into gypsum (cf. 96). 



Fehling's solution is not directly reduced by inulin. 



123. For the rapid recognition of inulin, the reagents for 

 sugar recommended by Molisch (V, 918) may be used (cf. 

 117). Thus the sphaerocrystals of inulin dissolve with a 

 very deep violet color, if the sections containing them are 

 treated with a 10$ alcoholic solution of a-naphtol, then with 

 a few drops of concentrated sulphuric acid, and are .then 

 slightly warmed under a cover-glass. 



But if thymol is added in the same way, a red color ap- 

 pears, according to Molisch. 



Green has recommended (I) orcin as a reagent for inulin. 

 The sections to be studied are saturated with an alcoholic 

 solution of orcin and boiled in hydrochloric acid. A deep 

 orange-red color then appears if inulin is present. Any 



